/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.mock.jndi;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.lang.Nullable;
import org.springframework.util.StringUtils;

import javax.naming.*;
import java.util.HashMap;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.Map;

/**
 * Simple implementation of a JNDI naming context.
 * Only supports binding plain Objects to String names.
 * Mainly for test environments, but also usable for standalone applications.
 *
 * <p>This class is not intended for direct usage by applications, although it
 * can be used for example to override JndiTemplate's {@code createInitialContext}
 * method in unit tests. Typically, SimpleNamingContextBuilder will be used to
 * set up a JVM-level JNDI environment.
 *
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @see SimpleNamingContextBuilder
 * @see org.springframework.jndi.JndiTemplate#createInitialContext
 */
public class SimpleNamingContext implements Context {

    private final Log logger = LogFactory.getLog(getClass());

    private final String root;

    private final Hashtable<String, Object> boundObjects;

    private final Hashtable<String, Object> environment = new Hashtable<>();


    /**
     * Create a new naming context.
     */
    public SimpleNamingContext() {
        this("");
    }

    /**
     * Create a new naming context with the given naming root.
     */
    public SimpleNamingContext(String root) {
        this.root = root;
        this.boundObjects = new Hashtable<>();
    }

    /**
     * Create a new naming context with the given naming root,
     * the given name/object map, and the JNDI environment entries.
     */
    public SimpleNamingContext(
            String root, Hashtable<String, Object> boundObjects, @Nullable Hashtable<String, Object> env) {

        this.root = root;
        this.boundObjects = boundObjects;
        if (env != null) {
            this.environment.putAll(env);
        }
    }


    // Actual implementations of Context methods follow

    @Override
    public NamingEnumeration<NameClassPair> list(String root) throws NamingException {
        if (logger.isDebugEnabled()) {
            logger.debug("Listing name/class pairs under [" + root + "]");
        }
        return new NameClassPairEnumeration(this, root);
    }

    @Override
    public NamingEnumeration<Binding> listBindings(String root) throws NamingException {
        if (logger.isDebugEnabled()) {
            logger.debug("Listing bindings under [" + root + "]");
        }
        return new BindingEnumeration(this, root);
    }

    /**
     * Look up the object with the given name.
     * <p>Note: Not intended for direct use by applications.
     * Will be used by any standard InitialContext JNDI lookups.
     *
     * @throws javax.naming.NameNotFoundException if the object could not be found
     */
    @Override
    public Object lookup(String lookupName) throws NameNotFoundException {
        String name = this.root + lookupName;
        if (logger.isDebugEnabled()) {
            logger.debug("Static JNDI lookup: [" + name + "]");
        }
        if ("".equals(name)) {
            return new SimpleNamingContext(this.root, this.boundObjects, this.environment);
        }
        Object found = this.boundObjects.get(name);
        if (found == null) {
            if (!name.endsWith("/")) {
                name = name + "/";
            }
            for (String boundName : this.boundObjects.keySet()) {
                if (boundName.startsWith(name)) {
                    return new SimpleNamingContext(name, this.boundObjects, this.environment);
                }
            }
            throw new NameNotFoundException(
                    "Name [" + this.root + lookupName + "] not bound; " + this.boundObjects.size() + " bindings: [" +
                            StringUtils.collectionToDelimitedString(this.boundObjects.keySet(), ",") + "]");
        }
        return found;
    }

    @Override
    public Object lookupLink(String name) throws NameNotFoundException {
        return lookup(name);
    }

    /**
     * Bind the given object to the given name.
     * Note: Not intended for direct use by applications
     * if setting up a JVM-level JNDI environment.
     * Use SimpleNamingContextBuilder to set up JNDI bindings then.
     *
     * @see org.springframework.mock.jndi.SimpleNamingContextBuilder#bind
     */
    @Override
    public void bind(String name, Object obj) {
        if (logger.isInfoEnabled()) {
            logger.info("Static JNDI binding: [" + this.root + name + "] = [" + obj + "]");
        }
        this.boundObjects.put(this.root + name, obj);
    }

    @Override
    public void unbind(String name) {
        if (logger.isInfoEnabled()) {
            logger.info("Static JNDI remove: [" + this.root + name + "]");
        }
        this.boundObjects.remove(this.root + name);
    }

    @Override
    public void rebind(String name, Object obj) {
        bind(name, obj);
    }

    @Override
    public void rename(String oldName, String newName) throws NameNotFoundException {
        Object obj = lookup(oldName);
        unbind(oldName);
        bind(newName, obj);
    }

    @Override
    public Context createSubcontext(String name) {
        String subcontextName = this.root + name;
        if (!subcontextName.endsWith("/")) {
            subcontextName += "/";
        }
        Context subcontext = new SimpleNamingContext(subcontextName, this.boundObjects, this.environment);
        bind(name, subcontext);
        return subcontext;
    }

    @Override
    public void destroySubcontext(String name) {
        unbind(name);
    }

    @Override
    public String composeName(String name, String prefix) {
        return prefix + name;
    }

    @Override
    public Hashtable<String, Object> getEnvironment() {
        return this.environment;
    }

    @Override
    @Nullable
    public Object addToEnvironment(String propName, Object propVal) {
        return this.environment.put(propName, propVal);
    }

    @Override
    public Object removeFromEnvironment(String propName) {
        return this.environment.remove(propName);
    }

    @Override
    public void close() {
    }


    // Unsupported methods follow: no support for javax.naming.Name

    @Override
    public NamingEnumeration<NameClassPair> list(Name name) throws NamingException {
        throw new OperationNotSupportedException("SimpleNamingContext does not support [javax.naming.Name]");
    }

    @Override
    public NamingEnumeration<Binding> listBindings(Name name) throws NamingException {
        throw new OperationNotSupportedException("SimpleNamingContext does not support [javax.naming.Name]");
    }

    @Override
    public Object lookup(Name name) throws NamingException {
        throw new OperationNotSupportedException("SimpleNamingContext does not support [javax.naming.Name]");
    }

    @Override
    public Object lookupLink(Name name) throws NamingException {
        throw new OperationNotSupportedException("SimpleNamingContext does not support [javax.naming.Name]");
    }

    @Override
    public void bind(Name name, Object obj) throws NamingException {
        throw new OperationNotSupportedException("SimpleNamingContext does not support [javax.naming.Name]");
    }

    @Override
    public void unbind(Name name) throws NamingException {
        throw new OperationNotSupportedException("SimpleNamingContext does not support [javax.naming.Name]");
    }

    @Override
    public void rebind(Name name, Object obj) throws NamingException {
        throw new OperationNotSupportedException("SimpleNamingContext does not support [javax.naming.Name]");
    }

    @Override
    public void rename(Name oldName, Name newName) throws NamingException {
        throw new OperationNotSupportedException("SimpleNamingContext does not support [javax.naming.Name]");
    }

    @Override
    public Context createSubcontext(Name name) throws NamingException {
        throw new OperationNotSupportedException("SimpleNamingContext does not support [javax.naming.Name]");
    }

    @Override
    public void destroySubcontext(Name name) throws NamingException {
        throw new OperationNotSupportedException("SimpleNamingContext does not support [javax.naming.Name]");
    }

    @Override
    public String getNameInNamespace() throws NamingException {
        throw new OperationNotSupportedException("SimpleNamingContext does not support [javax.naming.Name]");
    }

    @Override
    public NameParser getNameParser(Name name) throws NamingException {
        throw new OperationNotSupportedException("SimpleNamingContext does not support [javax.naming.Name]");
    }

    @Override
    public NameParser getNameParser(String name) throws NamingException {
        throw new OperationNotSupportedException("SimpleNamingContext does not support [javax.naming.Name]");
    }

    @Override
    public Name composeName(Name name, Name prefix) throws NamingException {
        throw new OperationNotSupportedException("SimpleNamingContext does not support [javax.naming.Name]");
    }


    private abstract static class AbstractNamingEnumeration<T> implements NamingEnumeration<T> {

        private Iterator<T> iterator;

        private AbstractNamingEnumeration(SimpleNamingContext context, String proot) throws NamingException {
            if (!"".equals(proot) && !proot.endsWith("/")) {
                proot = proot + "/";
            }
            String root = context.root + proot;
            Map<String, T> contents = new HashMap<>();
            for (String boundName : context.boundObjects.keySet()) {
                if (boundName.startsWith(root)) {
                    int startIndex = root.length();
                    int endIndex = boundName.indexOf('/', startIndex);
                    String strippedName =
                            (endIndex != -1 ? boundName.substring(startIndex, endIndex) : boundName.substring(startIndex));
                    if (!contents.containsKey(strippedName)) {
                        try {
                            contents.put(strippedName, createObject(strippedName, context.lookup(proot + strippedName)));
                        }
                        catch (NameNotFoundException ex) {
                            // cannot happen
                        }
                    }
                }
            }
            if (contents.size() == 0) {
                throw new NamingException("Invalid root: [" + context.root + proot + "]");
            }
            this.iterator = contents.values().iterator();
        }

        protected abstract T createObject(String strippedName, Object obj);

        @Override
        public boolean hasMore() {
            return this.iterator.hasNext();
        }

        @Override
        public T next() {
            return this.iterator.next();
        }

        @Override
        public boolean hasMoreElements() {
            return this.iterator.hasNext();
        }

        @Override
        public T nextElement() {
            return this.iterator.next();
        }

        @Override
        public void close() {
        }
    }


    private static final class NameClassPairEnumeration extends AbstractNamingEnumeration<NameClassPair> {

        private NameClassPairEnumeration(SimpleNamingContext context, String root) throws NamingException {
            super(context, root);
        }

        @Override
        protected NameClassPair createObject(String strippedName, Object obj) {
            return new NameClassPair(strippedName, obj.getClass().getName());
        }
    }


    private static final class BindingEnumeration extends AbstractNamingEnumeration<Binding> {

        private BindingEnumeration(SimpleNamingContext context, String root) throws NamingException {
            super(context, root);
        }

        @Override
        protected Binding createObject(String strippedName, Object obj) {
            return new Binding(strippedName, obj);
        }
    }

}
